In recent years, with advance in digital technology, electronic devices such as mobile information devices and information home appliances have been developed to provide higher functionality. As the electronic devices provide higher functionality, miniaturization and an increase in speed of semiconductor devices for use with the electronic devices are making rapid progress. Among them, the use of a large capacity nonvolatile memory, represented by flash memory, is rapidly expanding. Furthermore, as a next-generation new nonvolatile memory replacing the flash memory, there is on-going research and development of variable resistance nonvolatile semiconductor memory elements using what is called a variable resistance element. Here, the variable resistance element refers to an element which has a characteristic in which a resistance value reversibly changes depending on electric signals, and further is able to store information corresponding to the resistance value in a nonvolatile fashion.
As an example of the variable resistance element, nonvolatile semiconductor memory elements incorporating a variable resistance element in which a stack of transition metal oxides having different oxygen content percentages is used for a variable resistance layer are proposed. For example, PTL 1 discloses that the redox reaction is selectively generated at an electrode interface in contact with the variable resistance layer having a high oxygen content percentage to stabilize the resistance change.